At least 10 Grimsby Town supporters had their bras checked by stewards at Stevenage football club on Saturday.

A 70-year-old woman was among those left “mortified” by the searches outside Stevenage FC’s Lamex Stadium, the Guardian understands.

The EFL said on Monday night it had launched an investigation into the allegations.

A spokesman said: “The EFL has today been made aware of the contents of correspondence published by the Grimsby Town Mariners Trust and a media statement released by officials at Stevenage FC in relation to events that are alleged to have taken place at Saturday’s League Two game between Stevenage and Grimsby Town.

“At this current time the EFL’s security adviser is looking further into the matters raised and will be seeking the observations of both clubs. We are not in a position to make any further comment until such a time when all the facts have been made available and are fully considered.”

The EFL statement came after Stevenage FC said it had tightened security at the game over concerns that prohibited items may be smuggled into the ground by women or children.

The Hertfordshire club said the stewarding was “not typical” because they believed “high-risk groups” would be attending with the potential for antisocial behaviour.

It added: “The club takes these allegations seriously and will both study the CCTV footage and speak to the relevant parties to ensure that no infringements of accepted procedures took place.”

Grimsby Town reacted angrily on Monday night, saying they “fully refute having any finger of blame” pointed at them.

The Lincolnshire club said it had advised Stevenage before the game that “risk issues would be minimal” other than a few drinkers attending the fixture. The only small risk was the chance of smoke bombs from a small number of younger fans, aged 15-25, the club said.

It added: “GTFC does not condone searching of minors (under-13s) or the questioning of females about the contents of their underwear and fully supports the letter issued by the Mariners Trust.

“Each club is fully responsible for its own stewarding operation and must accept any consequences of proved failings on the day. On that note we fully support the EFL who are looking into the nature of the complaints raised and await their findings.”

A spokeswoman for Hertfordshire police said officers were at the match but were not involved in any of the searches carried out by stewards.

The force said: “At this stage no allegations have been made to Hertfordshire Constabulary in relation to the actions of stewards at the football match. If any allegations are made to police these will be fully investigated.

“Police were in attendance at the match due to intelligence regarding a previous game between Chesterfield and Grimsby Town, where there was public disorder and members of the public were injured.”